| 摘要 |
PURPOSE:To perform the highly precise high-speed rotation at a constant speed by providing an arbitrary current-value setting type constant current driving circuit, which excites the coils of a stepping motor at the current value corresponding to the voltage signal from a low-pass filter and maintains the current value corresponding to the voltage of the voltage signal. CONSTITUTION:A PWM signal corresponding to a changing duty ratio is generated by a PWM unit. The PWM signal is inputted into low-pass filters 104a and 104b. The voltage level in the step shape, which is expressed by the changing duty ratio of the PWM signal, is converted into the smooth, approximately continuous voltage signal. A constant current driving circuit 105 excites coils 107a-107d of a stepping motor with the current value, which is set in accordance with the voltage signal, and maintains the current value, which is set in accordance with the voltage of the voltage signal. Thus, the vibration of the motor is not generated, the rotation noises can be reduced and the high torque in comparison with dissipation power can be obtained. |
